1:To massively mess up at a job
2:Originally taken from many Football Manager Forums, this phrase refers to being sacked for doing something incredibly ambitious, such as attempting to sign Messi when managing a club like Stamford Daniels. Generally seen as attempting to pull off a douche move, and failing massively.
This phrase was named after a prominent member of theawaystand.co.uk, and has become a staple of its forums.
3: To get fired from a job after less than a week

"Foxo'd just 4 days after getting hired...classic Foxo."
"My ambition is not to be Foxo'd .. Wait, that happened last night."